Dual rate gaseous fuel burner assemblies

ABSTRACT

Dual rate gaseous fuel burner assemblies wherein a unitary burner is designed to operate at dual rates for full and standby operation in accordance with the fuel flow supplied from a single supply conduit. A flame sensing element is cooperatively disposed upon the burner assemblies such that both the main and standby flame patterns impinge upon the sensing element to provide an effective safety feedback signal for control of the fuel flow to the burner.

United States Patent [191 Braucltsiek et al.

[ 1 DUAL RATE GASEOUS FUEL BURNER ASSEMBLIES [75] Inventors: Henry C.Brauckslek, Buena Park;

Jay R. Katchka, Long Beach; I Theodore J. Dykzeul, Rolling Hills, all ofCalif.

[73] Assignee: Robertshaw Controls. Company,

Richmond, Va.

[22] Filed: June 22, 1971 [21] Appl. No.: 155,537

[52] US. Cl. 431/285, 434/347 [51] Int. Cl. F23g 9/00 [58] Field ofSearch 431/42, 80, 284,

1 [56] References Cited I UNITED STATES PATENTS 1,995,003 3/1935MacKenzie et a1. 239/419.$ 2,918,967 12/1959 Hays et a1. 239/4195 X 11113,754,853 Aug. 28, 1973 1,486,668 3/1924 Kielberg 239/4255 2.526.74810/1950 Hill 239/4256 X 3,561,901 2/1971 Jackson et a1. 431/284 FOREIGNPATENTS OR APPLICATIONS 408,842 4/1934 Great Britain..... 431/42 633,6741/1962 Canada 431/80 Primary Examiner-Edward G. Favors Attorney-Brenner,O'Brien & Guay [5 7] ABSTRACT Dual rate gaseous fuel burner assemblieswherein a unitary burner is designed to operate at dual rates for full Iand standby operation in accordance with the fuel flow supplied from asingle supply conduit. A flame sensing element is cooperatively disposedupon the'burner assemblies such that both the main and standby flamepatterns impinge upon the sensing element to provide an effective safetyfeedback signal for control of the fuel flow to the burner.

10 Claims, 7 Drawing Figures Patented Aug. 28, 1973 2 Sheets-Sheet 1.IIIIII viii! FIG. 2

INVENTORS, y C. Broucksiek 0y R. Kcnchko Henr J Theodore J. D

ykzeul BY f l' O RNEYs Patented Aug. 28, 19.73 3,754,853

2 Sheets-Sheet 2 INVENTORS, Henry C. Braucksiek Jay R. Korchko TheodoreJ. Dykzeul TORNEYS 1 DUAL RATE oAsEous'FuEL BURNER ASSEMBLIES BACKGROUNDOF THE INVENTION 1. Field of the Invention The present invention relatesto fuel burner systems and, more particularly, to dual rate gaseous fuelburner assemblies for use in such systems.

2. Description of the Prior Art The prior art, as exemplified by US.Pat. Nos. 1,763,295, No. 2,155,339, No. 2,220,247, No. 2,474,547, No.2,531,316, No. 2,840,152, No. 3,164,200, No. 3,405,999 and No.3,516,773, is generally cognizant of various types of burner apparatuswherein a main flame is selectively ignited by means of a standby orpilot flame. These prior art patents are representative of conventionalapproaches in the design of fuel burner systems which are capable ofproviding plural flame patterns, with a flame or heat sensing elementresponsive to only a single flame pattern for safety purposes. Systemsof this general type have been found to be disadvantageous inthatincomplete safety characteristics are exhibited thereby and,further, that the various burner assemblies used thereinare undulycomplicated in design and construction rendering them economicallyunsatisfactory in many instances.

SUMMARY OF THE INVENTION The present invention is summarized in a dualrate burner including a housing defining a closed annular chambersurrounding an open vertical air passage, a

single fuel inlet port supplying fuel to the, housing at high and lowrates, a flame spreader carried by the housing in spaced superpositiontherewith, and outlets defining burner orifices in the top of theannular chamber for supporting high and low rate flame patterns and fordirecting such flame patterns upwardly of the housing developing anupdraft through the open air passage.

It is an object of the present invention to simply and economicallyconstruct a burner assembly capable of developing plural flame patternsdependent upon the flow rate of fuel supplied thereto.

Another object of this invention is to construct a unitary burner havinga single inlet port and producing plural flame patterns.

This invention has another object in that a heat sensing element iscarried by burner apparatus in such a manner that main and standby flamepatterns produced thereat always impinge on the heat sensing element.

A further object of the present invention is to construct a dual rategaseous fuel burner supplied by a single conduit so as to eliminatetheneed for standby or pilot gas conduits.

Other objects and advantages of the present invention will becomeapparent from the following description of the preferred embodimentswhen taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of apreferred embodiment of a dual rate gaseous fuel burner assemblyaccording to the present invention;

FIG. 2 is a cross-sectional viewof the assembly of FIG. 1 showing theburner apparatus operating under a low-rate flame condition;

FIG. 6 is a top plan view of the burner apparatus of FIG. 5; and

FIG. 7 is a partial sectional view of the burner assembly of FIG. 1illustrating a modified flame spreader according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIGS. 1-4,the present invention is embodied in a gaseous fuel burner assemblyincluding a burner, indicated generally at 10, having a cylindricalhousing 12 which is open at both ends and, at its lower end, is deformedto define a concentric, smaller diameter cylindrical neck portion 14. Asingle inlet conduit 16 communicates with'the interior of housing 12 via.inlet port 18 which is defined by a wall of the housing intermediateits ends.

A cylindrical tube 20having an outer diameter equal to the innerdiameter of neck portion 14 of housing 12 is concentrically disposedwithin the housing 12 as. shown in FIGS. 2. and 3 with the lower end oftube 20 seam welded or otherwise suitably attached to the housing so asto provide an air-tight seal therebetween. Tube 20 has, at its upperend, an outwardly flared, frustro-eonical portion 22 which iscontiguously formed with a flutedcylindrical end portion 24 having anouter diameter equal to the inner diameter of housing 12. As canbe seenin FIG. 4, fluted portion 24 of cylindrical tube 20 cooperates withhousing 12 to define a plurality of circumferentially spaced outletports 26 for' the burner. Referring to FIGS. 2 and 3, the concentricarrangement of housingl2 and cylindrical tube 20 provides a hollow spacetherebetween which defines a gem erally cylindrical, annular chamber 28for receiving a flow of gas from inlet conduit 16, with chamber 28surrounding an open vertical air passage defined by tube 20.

Mounted upon inlet conduit I6 is a flame sensing as sembly, indicatedgenerally at 30, including a generally U-shaped upright mounting bracket32 which is affixed to conduit 16 in any suitable manner such as bywelding. The upright legs of bracket 32 are aligned in parallel and areobliquely disposed with respect to the base thereof, as can be seen inFIGS. 2 and 3. Each of the legs of bracket 32 defines an axially alignedaperture 34 and 36, respectively, with an annular collar 38 of aretaining clip disposed adjacent the periphery of aperture 36. Athermocouple 40 is mounted through apertures 34 and 36, and a suitablefastener such as the retaining clip 42 is'inserted in the aperture 3 6so as to secure the thermocouple 40 to the burnerassembly.

A flat, flame spreading plate 44 is mounted upon three equally spacedsupport legs .46 over burner 10 and is attached by any suitable meanssuch as spot welding. to a bent tab 48 formed at the upper end of eachleg. Each of the legs 46 extends partially across the radius of housing12 (FIG. 5) and has an arcuate tab 50 at a lower end thereof tofacilitate attachment to the housing 12 by welding or any other suitablemeans. It is noted that the apertures 26 defined by fluted cylindricalportion 24 of tube 20 are located in three equal segments or arcs aboutthe periphery of housing 12, and the aforementioned legs 46 are orientedso as to be positioned above the spaces formed between the threesegments whereby the burner flame does not directly impinge upon thelegs.

In operation, the dual rate burner assembly of FIGS. 1-4 is designed tobe used in cooperation with a control device (not shown) having a singleoutlet and adapted to provide dual rates of gas flow in accordance withpreselected standby or main burner modes of operation. Such a controldevice may also include an electromagnetic safety holding device, ofconventional design, which is connected to receive the generatedthermoelectric potential from thermocouple 40 when heated by the flamefrom burner apparatus 10. The holding device operates a safety valve forthe gas such that in the event no flame impinges upon the thermocouple40, the holding device will release the valve and safely cutoff the flowof fuel to the burner.

To initiateburner operation, the control device is set to its low-rateposition and the holding device is manually held in its reset positionwhereupon a low-rate flow of gas is fed to single inlet conduit 16 ofthe burner 10. The incoming gas enters chamber 28 of housing 12 underlow pressure and escapes upwardly through ports 26. Since tube 20 ishollow and is open at both ends, the gas escaping upwardly from ports26, when ignited, causes an updraft of air through tube 20 whereby thestandby or low-rate flame pattern illustrated in FIG. 2 is produced byburner '10. It is noted that the thermocouple 40 is supported by bracket32 in a slightly inclined position with the tip or flame responsive endthereof disposed for impingement by the standby flame. Thus, afterestablishment of the standby flame, the thermocouple 40 will be heatedso as to produce a sufficient energizing voltage for the electromagneticholding device in the gas control assembly (not shown) whereupon theholding device may be released with the safety shut-off valve held inits open position.

After release of the holding device, the control assembly is then set toits main or on position whereupon a hiGh-rate gas flow is establishedfor the burner. The low-rate flame pattern at the burner is thereforetransformed to a high-rate pattern, as shown in FIG. 3, with the BTUcapacity of the burner determined primarily by the depth of the flutesin the top portion 24 of tube 20. Since the gas from ports 26 is flowingat a much higher velocity than during standby operation, the flamecannot propagate down to the top of the burner and is spread outwardlyby the flame spreader 44. At this point, even though the gas velocity ismuch greater than during standby and even'though the flame producedduring full or main operation is spaced from the top surface of theburner, as illustrated, the disposition of thermocouple 40 is such thatthe tip thereof extends into the gas stream so as to disturb the fuelflow in the vicinity of the thermocouple. The turbulence caused by thethermocouple tip slows down the gas sufficiently to enable the flame topropagate downwardly so as to burn directly about the thermocouple asillustrated, whereupon the presence or absence of a high rate flame canbe safely and effectively monitored.

Once the demand for heating ceases, a low-rate flow of gas isreestablished to the burner 10 whereupon the standby flame pattern ofFIG. 2 is produced at the burner and may be maintained until the demandfor heat is once again developed. The dual rate burner 10 thus iscapable of continued cyclic operation between its high and low flamesunder thermostatic control in response to the rate of flow of gassupplied thereto. In the event that the flame at the dual rate burnershould be extinguished for any reason, when in either its high or lowflame mode, the thermocouple 40 will cool and the holding device (notshown) will be deenergized causing the release of the safety shut-offvalve to its off position thereby precluding raw fuel leakage.

During the cycling of the dual rate burner, it automatically changesbetween its high and low flame pat terns in accordance with the high andlow rates of fuel flow to the burner inlet 16. It should be noted thatdur ing both high and low rates, the flame impinges directly on theflame responsive element 40; furthermore, the contrary to conventionalburner apparatus, during low input conditions (FIG. 2) as well as highinput conditions (FIG. 3), the fuel flow exits from the single set ofoutlet ports 26. Such an arrangement eliminates the necessity of aseparate pilot or standby burner resulting in substantial cost reductionin manufacture and assembly. Additional cost reduction is apparent fromthe use of a single conduit 16 which delivers fuel to burner 10 at boththe high and low rates of flow; thus, there is no need for a separatepilot" conduit and no need for the accompanying fittings which are usedto fasten such a separate conduit to the burner and the control device.Furthermore, the burner 10 itself results in significant savings in viewof the extremely simplified nature of its design which permits fast andeconomical manufacture with reduced labor costs.

A modification of the dual rate burner assembly of FIGS. 1-4 isillustrated in FIGS. 5 and 6, and only the structure which differs fromthat of FIGS. 1-4 is being described in detail for the sake of brevity.Accordingly, the same reference numerals are being utilized for thoseelements previously described in connection with FIGS. 1-4, and similarreference numbers with added thereto are being utilized to identifyelements similar to those previously described.

As is shown in FIG. 5, housing 12 of burner apparatus is offset at itsupper end to define a flat annular shoulder or support ring 160 having aplurality of upstanding tabs 162 spaced about the periphery thereof soas to protect the low-rate or standby flame from drafts.

A cylindrical tube having an outer diameter equal to the inner diameterof neck portion 14 of housing 12 is concentrically disposed within thehousing and has an inverted annular channel 164 contiguously formed atits upper end as shown in FIG. 5. Channel 164 has a generally U-shapedcross-section and has an outer diameter equal to that of housing 12. Anannular flange 166 on the outer periphery of channel 164 is sealablyaffixed as by welding to shoulder of housing 12, as is the lower end oftube 120 and neck portion 14 of the housing. Tube l20and housing 12 thusform a hollow space which defines a generally cylindrical, annularchamber 128 which receives a flow of gas from inlet 18. A plurality ofcircumferentially spaced outlet ports 168 are defined by the upper wallor floor of annular channel 164, with the ports 168 disposed in threeequally spaced groups about the burner to prevent direct flameimpingement upon legs 46 of the flame spreader 44 as described inconnection with the structure of FIGS. 1-4.

substantially identical with that of the burner 10 of FIG. 1 and thuswill not be described again for the sake of brevity. It is noted thatwhile the outlet ports of the embodiment of FIGS. 5 and 6 are in theform of spaced apertures 168, as compared with the fluted constructionof burner 10 of FIG. 1, the standby and main flame patterns produced byburners I0 and 110 are substantially the same and, in both embodiments,the high and low flames impinge directly upon thermocouple 40 to enablefull-cycle flame detection and control. It is also noted that the tabsor baffles 162 (FIG. 5) serve to prevent undesired flame outage as maybe caused by drafts.

A modification of the flame spreader 44 of FIG. 1 is shown in FIG. 7.Flame spreader 144 of FIG. 7 is substantially similar to that of FIG. 1with the exception that the central portion thereof is deformed toprovide a smooth, radially symmetrical bulge 170 which faces the top ofthe burner 10. The deformed shape of flame spreader 144 illustrated inFIG. 7 produces a modification in the high-rate or main flame pattern ofthe burner apparatus and may be used in those applications where such amodified flame pattern may be desired without in any way detracting fromthe operation of the dual rate burner assemblies of the presentinvention.

In accordance with the present invention, the unitary dual rate burnerexhibits desired performance characteristics at two levels of operation,main flame and standby flame, thereby solving a long standing problem;namely, how to obviate the need for a pilot burner in a gas burnersystem. The significance of such performance becomes apparent whencomparing the increase of the input rate of gas from the low ratemaintaining the standby flame to the high rate maintaining the mainflame. For example, a typical pilot burner would have an input rate of750 to 1000 BTU per hour at a particular pressure generally measured ininches of a water column and such a pilot burner could be operatedbetween two flame levels such as is shown in U. S. Pat. No. 3,405,999.However, in prior art devices of this type, the increase in the inputrate is usually limited to a multiplier of approximately three. Sincethe input rate is proportional to the square root of the gas pressure,an increase in the input rate in such a conventional pilot burner to therate normally desired for a main flame, which is considerably greaterthan the standby or pilot rate, would result in a relatively high gaspressure which creates a number of serious problems such as blowing mostif not all of the flame away from the flame sensing thermocouple andeven blowing the entire flame out. Thus, a conventional pilot burnerlacks the capability of operating at the relatively high input ratenecessary to sustain a main flame. The present invention, on the otherhand, has the particular advantage of a single burner capable ofoperating at a standby flame level as well as at a main flame level andfurther capable of maintaining direct flame impingement on a flamesensing device at both levels.

Inasmuch as the present invention is subject to many variations,modifications and changes in detail, it is intended that all mattercontained in the foregoing description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is: l. A dual rate gas burner comprising burner housingmeans defining a closed annular chamber surrounding an open vertical airpassage, said burner housing means including a cylindrical housingmember and a cylindrical, hollow tube concentrically disposed withinsaid housing member and affixed therein to define said annular chambertherebetween,

a single fuel inlet port for said housing means supplying fuel theretoat high and low rates,

flame spreading means carried by said housing means, said flamespreading means being disposed in spaced super-position with saidhousing means for spreading a flame issuing therefrom when a high rateof fuel flow is supplied to said housing means, and

outlet means in said housing means defining burner orifice means in thetop of said annular chamber for supporting high and low rate flamepatterns in accordance with the rate of fuel supplied thereto and fordirecting both of such flame patterns upwardly of said housing meansdeveloping an updraft through said open air passage,

said cylindrical housing member having annular shoulder on an upper endthereof and a plurality of upstanding tabs spaced about the periphery ofsaid flange.

2. The invention as recited in claim 1 wherein said cylindrical tube hasan outwardly flared, fluted upper end cooperating with said housingmember to define a plurality of burner outlet ports comprising saidburner orifice means, and wherein the lower end of said tube issealingly secured to the lower end of said housing member.

3. The invention as recited in claim 1 wherein said hollow tube has aninverted annular channel contiguously formed on an upper end thereof,and wherein said burner orifice means comprises a plurality of spacedburner outlet ports in the floor of said channel.

4. The invention as recited in claim 3 wherein said hollow tube has anannular flange on the periphery of said channel, and wherein said flangeis sealingly secured with said shoulder of said housing member.

5. The invention as recited in claim 1 wherein said flame spreadingmeans comprises a flat plate supported upon a plurality of legs affixedto said housing means.

6. The invention as recited in claim 5 wherein said flat plate iscentrally deformed to define a smooth, radially symmetrical bulge oversaid burner orifice means.

7. A multiple rate gas burner and flame sensor combination comprising amultiple rate burner having a single inlet port adapted to be connectedwith a source of gas, and outlet means establishing a small standbyflame directly adjacent said outlet means and the same said outlet meansalternately establishing a larger main flame spaced from said outletmeans by the velocity of gas issuing therefrom,

a flame sensor, and

means for locating said flame sensor proximate to said multiple rateburner adjacent said outlet means such that said small standby flamedirectly impinges upon said flame sensor and said larger main flameprojects beyond said flame sensor, said flame sensor being disposed in aposition to develop a decreased-velocity turbulence in the gas flowissuing from said outletmeans when said larger main flame is establishedwhereby a portion locating means includes attaching means carried uponsaid inlet conduit, and wherein said flame sensor is oliliquelysupported upon said attaching means.

10. The invention as recited in claim 7 including flame spreading meansmounted in superposition with said multiple rate burner for spreadingthe larger main flame from said outlet means.

1. A dual rate gas burner comprising burner housing means defining aclosed annular chamber surrounding an open vertical air passage, saidburner housing means including a cylindrical housing member and acylindrical, hollow tube concentrically disposed within said housingmember and affixed therein to define said annular chamber therebetween,a single fuel inlet port for said housing means supplying fuel theretoat high and low rates, flame spreading means carried by said housingmeans, said flame spreading means being disposed in spacedsuper-position with said housing means for spreading a flame issuingtherefrom when a high rate of fuel flow is supplied to said housingmeans, and outlet means in said housing means defining burner orificemeans in the top of said annular chamber for supporting high and lowrate flame patterns in accordance with the rate of fuel supplied theretoand for directing both of such flame patterns upwardly of said housingmeans developing an updraft through said open air passage, saidcylindrical housing member having annular shoulder on an upper endthereof and a plurality of upstanding tabs spaced about the periphery ofsaid flange.
 2. The invention as recited in claim 1 wherein saidcylindrical tube has an outwardly flared, fluted upper end cooperatingwith said housing member to define a plurality of burner outlet portscomprising said burner orifice means, and wherein the lower end of saidtube is sealingly secured to the lower end of said housing member. 3.The invention as recited in claim 1 wherein said hollow tube has aninverted annular channel contiguously formed on an upper end thereof,and wherein said burner orifice means comprises a plurality of spacedburner outlet ports in the floor of said channel.
 4. The invention asrecited in Claim 3 wherein said hollow tube has an annular flange on theperiphery of said channel, and wherein said flange is sealingly securedwith said shoulder of said housing member.
 5. The invention as recitedin claim 1 wherein said flame spreading means comprises a flat platesupported upon a plurality of legs affixed to said housing means.
 6. Theinvention as recited in claim 5 wherein said flat plate is centrallydeformed to define a smooth, radially symmetrical bulge over said burnerorifice means.
 7. A multiple rate gas burner and flame sensorcombination comprising a multiple rate burner having a single inlet portadapted to be connected with a source of gas, and outlet meansestablishing a small standby flame directly adjacent said outlet meansand the same said outlet means alternately establishing a larger mainflame spaced from said outlet means by the velocity of gas issuingtherefrom, a flame sensor, and means for locating said flame sensorproximate to said multiple rate burner adjacent said outlet means suchthat said small standby flame directly impinges upon said flame sensorand said larger main flame projects beyond said flame sensor, said flamesensor being disposed in a position to develop a decreased-velocityturbulence in the gas flow issuing from said outlet means when saidlarger main flame is established whereby a portion of said main flamepropagates back toward said outlet means to surround said flame sensor.8. The invention as recited in claim 7 wherein said multiple rate burnerincludes housing means defining a closed annular chamber surrounding anopen vertical air passage and an inlet conduit connected with saidhousing means at said single inlet port and extending radially from saidannular chamber.
 9. The invention as recited in claim 8 wherein saidlocating means includes attaching means carried upon said inlet conduit,and wherein said flame sensor is obliquely supported upon said attachingmeans.
 10. The invention as recited in claim 7 including flame spreadingmeans mounted in superposition with said multiple rate burner forspreading the larger main flame from said outlet means.